<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <link rel="stylesheet" href="https://cdn.bootcss.com/twitter-bootstrap/4.3.1/css/bootstrap.css">
</head>
<body>
  <h1>登陆</h1>
  <form class="container col-6">
    <div class="form-group">
      <label>用户名</label>
      <input class="form-control" type="text">
    </div>
    <div class="form-group">
      <label for="">密码</label>
      <input class="form-control"  type="password">
    </div>
    <div class="form-group">
      <button class="btn btn-primary btn-block" type="submit">登陆</button>
    </div>
  </form>
</body>
</html>